Infidelity Support Group
Any relationship in which one partner engages willfully in sexual relations with another outside of the partnership is considered to have experienced infidelity. This breach of trust is often traumatizing for the faithful partner as well as the relationship, and support is often needed to heal emotionally and to decide whether or not the relationship should continue after...
Next time, send him a text back stating "I will only accept contact from you in regards to the specific business of seeing Mo." I don't know your story, so if there Mo is not his, and he has no rights, then leave it at "I will no longer accept any contact from you".
And then delete any text, voice-mail, email, etc. that does not have to do with anything actually real about Mo.
And never, ever, ever, ever actually pick up the phone when he calls. Let him leave a voice-mail so you can control your reactions.